Wave washers or wave springs are wavy metal washers designed to provide a compensating spring force and sustain a load or absorb shock.  Wave washers are commonly called spring washers.  Spring washers are disks of metal that are formed in an irregular shape so that when the washer is loaded it deflects, acts like a spring, and provides a preload between two surfaces.  Washers are disks of metal or non-metallic material placed beneath a nut, an axle bearing, or a joint, to relieve friction, prevents leakage, isolate, prevent loosening or distribute pressure. There are many different types of washers and washer type products for a variety of applications.